This invention relates to a hydrocarbon-soluble composition which is useful in inhibiting the corrosion of a corrodible metal material. More particularly, this invention relates to a hydrocarbon-soluble composition comprising the reaction product obtained by the acid-catalyzed oligomerization of an alkylaniline, formaldehyde and an aromatic compound. The invention further relates to a method of inhibiting corrosion in corrodible metals.
Corrosion inhibition in acid systems has been the subject of considerable interest in recent years. In industrial cleaning operations, where aqueous solutions of acid serve to remove scale and other deposits from metallic surfaces of industrial equipment, the inhibitors are used to reduce acid attack on the metals of construction during the cleaning operations. In processing operations where some acid is present or may be generated, inhibitors are introduced to reduce the corrosiveness of the acid. In oil well operations, corrosion inhibitors are introduced during various treatment stages and during secondary recovery operations. In all these operations, the corrosion inhibitor is in a form which is dispersible and preferably miscible in the liquid medium of the particular system.
Since the industrial equipment being protected by the inhibitor is often of considerable value or is often difficult and expensive to replace, significant importance has been given to the development of new and improved corrosion inhibitors. One area of such interest has been the organic inhibitors such as the amines, ketones, sulfides, acetylenic alcohols and the like. In respect to the amines or to their acid salts commonly formed in the acidic systems, fatty amines having one or more amine groups have been recognized as effective inhibitors. Rosin amines have also been used as corrosion inhibitors as have their oxyalkylated derivatives. In addition, various polymeric resins with amine functionalities have been used to some extent.
U.S. Pat. No. 3,770,377 discloses a method for preventing corrosion of metals by an acidic environment by utilizing a corrosion inhibitor which is the reaction product formed by reacting, in the liquid phase and under neutral conditions, at least one carbonyl compound and at least one amine containing a plurality of primary or secondary amino groups. Specific amines taught by this patent include hexamethylene diamine and 1,8-diaminonaphthalene. Specific carbonyl compounds employed include formaldehyde and cyclohexanone.
U.S. Pat. No. 4,554,090 discloses a combination corrosion and scale inhibitor composition comprising the reaction product of (a) a heterocyclic nitrogen containing compound selected from alkylpyridine, alkylpyrimidine, alkylimidazole, alkylimidazoline, quinoline and quinaldine, (b) an aldehyde and (c) a phosphoric acid constituent.
U.S. Pat. No. 3,977,981 discloses a method for inhibiting corrosion of corrodible metals utilizing a 14-membered or 16-membered macrocyclic tetramine.
U.S. Pat. No. 4,511,480 discloses a method of inhibiting corrosion of ferrous metals by employing a phosphate ester of an oxyalkylated thiol.
U.S. Pat. No. 4,089,789 discloses a method for inhibiting corrosion of ferrous metal in an acid system utilizing an oxyalkylated phenolic inhibitor comprising the reaction product of (a) an alkylene oxide and (b) a phenolic compound having two non-oxyalkylatable, saturated tertiaryamino alkylene groups.